Lathes of various sorts are used to mechanically shape workpieces for industrial and commercial purposes. All lathes have a stationary headstock which includes a driven spindle and a revolving chuck. Certain lathes utilize a hollow spindle. A workpiece such as an elongated bar is passed into and through the hollow spindle until it reaches the jaws of the chuck. One end of the workpiece can extend just beyond the chuck where a cutting tool is able to engage the workpiece as the workpiece rotates to provide a desired cut or shape. The workpiece can extend more fully through the chuck and, in some lathes, is supported at a second end by a movable tailstock. In either case, an end portion of the workpiece remains within the hollow spindle.
A spindle liner is conventionally used with elongated workpieces which have an end portion which remains within the spindle while another end is being machined. The spindle revolves at several hundred revolutions per minute. It is necessary that the workpiece be concentrically aligned within the spindle and rigidly supported to alleviate workpiece shattering. The spindle liner serves this purpose. It is a tubular member which has an inside diameter to slideably receive the workpiece with a minimum of dead space. A set of annular bearing rings are secured to an outside surface of the tubular member. The bearing rings have an outside diameter which allows the spindle liner to fit into the hollow spindle of the lathe and bear against its walls. Necessarily, there will be a number of different sized spindle liners for each lathe. Basically, a spindle liner with a properly sized inside diameter tubular member is needed for each of the different sized workpieces that are to be machined.
In use, a particular spindle liner is selected from a set of spindle liners depending on the workpiece to be machined. The spindle liner is properly inserted into the lathe and secured to it. A mounting flange near one end of the spindle liner and a set of bolts are often used to bolt the spindle liner to the lathe. When a different sized workpiece is to be machined, it is necessary to unbolt and remove the first spindle liner. The next spindle liner is then positioned and bolted to the lathe. This is a time consuming task. If several different sized workpieces are being processed daily, then the need to constantly change spindle liners becomes a serious productivity negative.
There have been attempts to solve the well recognized problem of spindle liner change-over experienced by many shops. U.S. Pat. Nos. 3,927,585, 4,058,036 and 4,149,437 all contain disclosures of spindle liners which have adjustable clamping means within a tubular member. The clamping means are able to accommodate several different diameters of workpieces. Accordingly, a single spindle liner is permanently mounted in the hollow spindle of the lathe. Thereafter, the clamping means within the spindle liner is adjusted according to need to handle virtually any cross-dimension size of workpiece. Unfortunately, the disclosed adjustable spindle liners are rather complex in design. This necessarily makes the spindle liners costly. It also creates problems in use.
There has been developed a spindle liner and spindle liner assembly which addresses the main drawback associated with the widely used conventional spindle liners. That being the excessive time involved with having to change spindle liners every time a different sized workpiece is to be machined. In accord with a long felt and well recognized need, there has now been developed a spindle liner with a quick-change feature. Spindle liners having the feature are readily installed and replaced. Down time normally associated with changing of spindle liners is significantly reduced. The improved spindle liners and spindle liner assemblies of the invention have the quick-change feature benefit without associated drawbacks of complexity of design, significant increase in cost or added skill in lathe operation.